Abstract Pseudomonas aeruginosa is an important opportunistic pathogen of humans. It is the principal cause of morbidity and mortality in Cystic Fibrosis (CF) patients and a major cause of hospital-acquired pneumonia. We are proposing to study a conserved putative signaling pathway that we have shown is critical for cell growth and for resistance to aminoglycosides in P. aeruginosa. At the center of this pathway are the PA2797 and PA2798 proteins, about which relatively little is known. In Aim 1 we propose to test the hypothesis that PA2797 enhances the intrinsic resistance of the organism to aminoglycosides by functioning as a so-called anti-anti-? factor. In particular, we will attempt to identify genes that are positively regulated by PA2797 and that specifically contribute to aminoglycoside resistance. In Aim 2 we will determine whether PA2797 and PA2798 govern the growth of P. aeruginosa by modulating the interaction between a component of the nitrogen-related phosphotransferase system and a small protein we have identified. Our proposed studies have the potential to reveal how a novel signal transduction pathway promotes the growth and antibiotic resistance of an important pathogen. Moreover, because cells lacking PA2797 or PA2798 are defective for growth and are considerably more susceptible to the bactericidal effects of tobramycin, the frontline antibiotic used in the treatment of CF patients, our proposed studies could have implications for the development of adjunctive therapies for treating P. aeruginosa infections.